It's all about turnout. As there are, apparently, only 3-6% (or so) of actual undecided voters, this is all about base maximization.

Telling a group of people whose ancestors had once been slaves that the opposing party intends to reinstitute slavery could sort of motivate people.

The latest Rasmussen poll of likely voters finds Romney pulling in 9 percent of African American support, and African Americans making up 12 percent of the total electorate. If that turns out to be the case in November, Obama would still do better than Kerry, but about 1.5 points worse than he did in 2008, taking into account the black vote alone.

The vital context here is Obama’s decline among white voters. This week, the Rasmussen poll finds him winning the support of just 35 percent of likely white voters, compared to 43 percent support from whites in 2008....

So, Obama really needs African Americans to come through for him about strongly as they did in 2008. Right now, that looks like a questionable proposition, which may help explain Biden’s remarks this week.

Moving forward, we should expect more of the same from the Democrats.

I made this point to my punching bag @dumme -- it sure seems like there's a coordinated effort to stoke enthusiasm among Obama's base, and since he can't run on his record, that enthusiasm will have to come from hatred of the opposition.

I Wish Conservatives Would Stop Injecting Race Into This Campaign At Every Turn:How dare us.

RUSH LIMBAUGH: “In many ways — especially for progressives — [Obama] is too white for them. He plays golf, he’s too cozy with bankers. But when it comes to knowing how to fight, he’s black."